Method of making bags



Nov. 7, 1939. 'r. M. AVERY METHOD OF MAKING BAGS Filed July 17, 1937 True 1?. Avery,

QIW M" atented Nov. 7, 1939 STATES PAT'E OFFICE METHOD OF MAKING BAGS application .luly 1'7, 1937, Serial No. 154,295

3 @Iaims.

The present invention relates to improvements in paper bags, and more particularly to those of the so-called satchel bottom type.

Bags of this type are usually. closed at the bottom by folding inwardly the longitudinal edges of the bag tube and then folding and pasting or securing the opposite fiat sides of the bag tube onto the previously folded edges, and in some bags of this type longitudinal slits are formed in the last folded portions of the bag bottom to pro-' I. vide substantially rectangular flaps. In using bags thus made as containers for powdery or finely divided material, such material sifts out between the overlapping flaps, and in bags having slits in the bottom folds, there has been a tendency for the bottom flaps to tear beyond the inner ends of the slits under the pressure of the material in the bag, thereby weakening or destroying the bag bottom. The primary object of the present invention is to provide a bag having a bottom formed with overlapping folds which are united or secured together in a manner which will render the bag sift-proof.

Another object is to provide a bag bottom of the type having slits in its bottom flaps which is not only rendered sift-proof but the slits are effectively reinforced against tearing beyond their inner ends under the stresses imposed thereon by the pressure of the material in the bag or from other causes.

A further object is to enable such a sift-proof and reinforced bag to be produced while the bag is being manufactured rapidly on a bag machine.

In the accompanying drawing:

Fig. 1 is a perspective view of a bag made in accordance with the present invention;

Fig. 2 is a diagrammatic view showing a section of a web-from which the improved bag may be made, this view indicating the lines on which the lower end of the bag tube made from such web is folded to-form the bottom flaps and the paste spots applied to secure the bottom flaps together to render the bag sift-proof and to reinforce the bag material to prevent tearing thereof beyond the slits;

Fig. 3 is a perspective view of the partially completed bag, showing the manner in which the bottom folds are made;

Fig. 4 is a longitudinal section taken on the line t-t in Fig. 1; and

Fig. 5 is a longitudinal section taken on the line 55 in Fig. 1.

Similar parts are designated by the same reference characters in the different views.

The improved bag, as shown in the present instance, is made from a strip or web I of paper or other flexible foldable material. .This web may be fed longitudinally into a bag machine of the conventional type, but during its advance, a pair 5 of paste spots 2, 2 are applied to the portion of the web intermediate its width and between the longitudinal lines 3 and t on which the web is folded to form the bag tube, before the tube is completely formed or before the longitudinal seam is pasted down, andpreferably while the web is in its flat unfolded form, and when the bag tube is subsequently folded on the lines 3 and 4, the paste spots will be opposite the folded longitudinal margins of the web and paste from the spots 2, 2 will be transferred to such folded portions of the web and thus provide the paste spots 2', 2' thereon. A longitudinal paste line 5 is also applied to a longitudinal edge of the web, preferably when the paste spots 2, 2 are applied, to form the longitudinal seam 6, when the web is folded on the lines 3 and 4 to form the bag tube.

The paste spots 2,2 and 2', 2' are applied to those portions of the bag tube which will be opposite to the inner ends of the longitudinal slits I 25 which may be subsequently made in the bag bottom in the usual and well known way.

The bag bottom may be formed in a manner usual in bag making machines, by folding the longitudinal edges at the lower end of the bag tube inwardly on the diagonal lines. 8 and 9 and I0 and II, thus separating the paste spots 2, 2' from the paste spots 2, 2 andopening the bottom of the tube and forming the bottom flaps I2 and I3 respectively, thus bringing the inner surfaces of the flaps I2 and I3 against the paste spots 2, 2 and 2', 2 and thereby causing the flaps to be secured and sealed against the remaining bottom flaps I4 and I5 which are formed as continuations of the flat sides of the bag tube. Since these paste spots secure the flaps I2 and I3 to the flaps I4 and i5 where these flaps overlap and at the inner ends of the slits "I, the double thickness of the material thus provided affords reinforcements which will resist and prevent sifting or leaking at the ends of the slits.

After paste lines I6, I1 and I8 have been applied in the usual 'or any other suitable way to the flaps I2, I3 and I5, as shown in Fig. 3, the flap It is folded against the flaps I2 and I3 on the fold line I9, and the flap I5 is folded on the fold line 20 against the folded flap I l and the exposed and gummed portions of the flaps I2 and I3, and the bag bottom is then completed.

During the forming of the bags from the web,

ends of the slits so that bursting of the bag bottom at the inner ends of the slits is effectively prevented.

Bags according to the present invention may be made rapidly by the method and apparatus disclosed fully in my copending application, Ser. No. 154,296, filed July 17, 1937.

I claim as my invention:

1. The method of making bags which comprises forming a web into a tube, applying spots of paste to the web before the tube is completely formed, transferring paste from said paste spots applied to one portion of the web to unpasted areas on another portion thereof, separating the portion of the web to which the paste spots have been applied relatively to the portion thereof to which the paste was transferred, and folding an end of the tube and overlapping and securing together portions thereof by said paste spots.

2. The method of making bags which comprises applying spots of paste to areas of a portion of a sheet of material which is to form one side of a tube, folding the sheet into a tube and thereby transferring paste from the spots applied to one side of the tube to unpasted areas on the other side thereof, slitting an end of the tube to points in proximity to said paste spots to define bottom closing flaps, separating the portion of the side of the tube to which the paste spots have been applied from the other side of the tube to which the paste was transferred, and overlapping portions of the bottom closing flaps and uniting and sealing them by said paste spots.

3. The method of making bags which comprises initially applying spots of paste to areas of a portion of a sheet of material which is to form one side of a tube, folding the sheet into a tube with said paste spots located interiorly thereof and transferring paste from said paste spots on one side of the tube to interior unpasted areas of the other side of the tube, slitting the bottom end of the tube to points in proximity to said paste spots to define bottom flaps, separating the side of the tube to which the paste spots were initially applied relatively to the other side of the tube to which paste was transferred, and opening the slit end of the tube and folding the same to form bottom flaps portions of which overlap and are secured together and sealed by said paste spots.

TRUE M. AVERY. 

